Battery management system and method of dynamically allocating charging current

ABSTRACT

A battery management system includes a power converter, a first switch, a second switch, a first detecting unit, and a CPU. The power converter is configured to divide current provided by the power supply into a first and a second output current, according to a working current of a system load in a normal state, the first output current is used to power the system load, and the second output current is used to charge a battery unit. The CPU is configured to determine whether the value of current detected by the first detecting unit is greater than a threshold value, and further controls turning on the first switch to power the system load using the first output current, and turn on the second switch to charge the battery unit using the second output current.

BACKGROUND

1. Technical Field

The present disclosure relates to battery management systems, andparticularly, to a battery management system and a method of dynamicallyallocating charging current.

2. Description of the Related Art

Normally, a power supply management system provides some of current foractivating and maintaining a system load, and directs the rest of thecurrent for charging a battery. Furthermore, the current used by theload is changing all the time, but the battery is charged with a fixedcurrent value, which is inefficient and may result in battery chargetime being longer than desired.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily drawn to scale, theemphasis instead being placed upon clearly illustrating the principlesof a battery management system and a method capable of dynamicallyallocating charging current. Moreover, in the drawings, like referencenumerals designate corresponding parts throughout the several views.

FIG. 1 is a block diagram of a battery management system in accordancewith an exemplary embodiment.

FIG. 2 is a flowchart of a method for dynamically allocating chargingcurrent in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, a battery management system 100 includes a powersupply 10, a system load 11, and a battery unit 12. The power supply 10and the battery unit 12 are both employed to power the system load 11,and the battery unit 12 can be charged by the power supply 10.

The battery management system 100 further includes a power converter 13,a CPU 14, a first detecting unit 15, and a second detecting unit 16. Theinput of the power converter 13 is connected to the power supply 10, andconfigured to divide the current generated by the power supply 10 intotwo output currents (e.g., a first output current and a second outputcurrent) according to a working current of the system load 11 in anormal state. The first output current is used to power the system load11, and the second output current is used to charge the battery unit 12.The value of the first output current is changes with the demand of thesystem load 11, and the value of the second output current is variesinversely with changes in the first output current. For example, supposethat the working current of the system load 11 in the normal state is40A and, then the current is divided so that the first output current is40A and the second output current is 50A. If the system load 11 drawsmore current, such as 50A, the first output current becomes 50A and thesecond output current becomes 40A. The maximum value of the currentcharging the battery unit 12 can be set to equal to the maximum value ofthe current provided by the power supply 10.

The first detecting unit 15 is connected between the input of the powerconverter 13 and the CPU 14, and configured to detect the current whichis generated by the power supply 10. The second detecting unit 16 isconfigured to detect the second output current.

The battery management system 100 further includes a first switch 17 anda second switch 18. When the second switch 18 is turned to forwardconduction, the second output current is used to charge the battery unit12, and when the second switch 18 is turned to opposite conduction,current is provided by the battery unit 12 to power the system load 11.

The CPU 14 is configured to determine whether the current detected bythe first detecting unit 15 is greater than a threshold value which is acurrent used to normally power the system load 11. If yes, the CPU 14controls to turn on the first switch 17 and the second switch 18 inforward conduction, and the first output current is used to power thesystem load 11 and the second output current is used to charge thebattery unit 12. If no, the CPU 14 controls to turn off the first switch17 and the second switch 18.

Normally, when the charging current is less than a predetermined value,namely, a cut-off current, the battery unit 12 is determined to be full.However, in the battery management system 100, due to the value of thefirst output current being changeable, the value of the second outputcurrent is inversely changes accordingly. The CPU 14 further determineswhether the second output current detected by the second detecting unit16 is less than the cut-off current, and whether the current detected bythe first detecting unit 15 is less than the maximum current valueprovided by the power supply 10 at the same time. If yes, the CPU 14determines the process of charging the battery unit 12 is to befinished, and turns off the second switch 18, thereby preventing the CPU14 from mistakenly ending charging the battery unit 12.

Furthermore, if the second output current used to charge the batteryunit 12 decreases to zero as detected by the second detecting unit 16,the CPU 14 determines the system load 11 is drawing all the provided bythe power supply 10. In such case, the second switch 18 is turned toforward conduction, and the battery unit 12 can provide additionalcurrent to the system load 11 as an auxiliary power supply (shown indotted line section).

FIG. 2 is a flowchart of a method for dynamically allocating chargingcurrent implemented by the battery management system 100.

In step S20, the CPU 14 determines whether the value of the currentprovided by the power supply 10 detected by the first detecting unit 15is greater than a threshold value which is a current used to normallypower the system load 11. If yes, the procedure goes to step S21,otherwise, the procedure returns to step S20.

In step S21, the CPU 14 controls turning on the first switch 17 andturning the second switch 18 to a forward conduction.

In step S22, the power converter 13 divides the current into the firstoutput current and the second output current according to a workingcurrent of the system load in a normal state.

In step S23, the CPU 14 determines whether the value of the secondoutput current used to charge the battery unit 12 detected by the seconddetecting unit 16 is less than the cut-off current. If yes, theprocedure goes to step S24, otherwise, the procedure returns to stepS23.

In step S24, the CPU 14 determines whether the current value detected bythe first detecting unit 15 is less than the maximum current valueprovided by the power supply 10. If yes, the procedure goes to step S25,otherwise, the procedure returns to step S24.

In step S25, the CPU 14 determines the process of charging the batteryunit 12 is finished, and turns off the second switch 18.

In step S26, the CPU 14 determines whether the value of the secondoutput current used to charge the battery unit 12 decreases to zero. Ifyes, the procedure goes to step S27, otherwise, the procedure returns tostep S26.

In step S27, the CPU 14 controls the second switch 18 to turn toopposite conduction, the battery unit 12 provides current to the systemload 11 as an auxiliary power supply.

It is understood that the present disclosure may be embodied in otherforms without departing from the spirit thereof. Thus, the presentexamples and embodiments are to be considered in all respects asillustrative and not restrictive, and the disclosure is not to belimited to the details given herein.

1. A battery management system, comprising: a system load; a batteryunit; a power converter for being connected to a power supply,configured to divide current provided by the power supply into twooutput currents, according to a working current of the system load in anormal state, wherein a first output current is used to power the systemload, and a second output current is used to charge the battery unit; afirst switch; a second switch; a first detecting unit connected to theinput of the power converter, configured to detect the current which isprovided by the power supply; and a CPU, configured to determine whetherthe value of the current detected by the first detecting unit is greaterthan a threshold value, and further controls to turn on the first switchto power the system load by the first output current, and turn on thesecond switch to charge the battery unit by the second output current ifyes.
 2. The battery management system as recited in claim 1, wherein thecurrent threshold is a current used to normally power the system load.3. The battery management system as recited in claim 1, wherein amaximum value of the current charging the battery unit is set to equalto the maximum value of the current provided by the power supply, andthe value of the first output current is changes with the demand of thesystem load, and the value of the second output current is variesinversely with changes in the first output current.
 4. The batterymanagement system as recited in claim 1, further comprising a seconddetecting unit configured to detect the second output current.
 5. Thebattery management system as recited in claim 4, wherein when the valueof the second output current detected by the second detecting unit isless than a cut-off current value of the battery unit, and the currentvalue detected by the first detecting unit is less than the maximumcurrent value provided by the power supply at the same time determinedby the CPU, the CPU determines the process of charging the battery unitto be finished, and controls to turn off the second switch.
 6. Thebattery management system as recited in claim 1, wherein when the valueof the current provided by the power supply is less than the thresholdvalue, the CPU is further configured to turn off the first switch andsecond switch.
 7. The battery management system as recited in claim 1,wherein when the second switch is turned to forward conduction, thesecond output current provided is used to charge the battery unit, andwhen the second switch is turned to opposite conduction, the currentprovided by the battery unit is used to power the system load.
 8. Thebattery management system as recited in claim 7, wherein when the valueof the second output current decreases to zero at one moment, the CPUdetermines the system load is drawing all the provided by the powersupply, then controls the second switch to turn to forward conduction,and the battery unit can provide additional current to power the systemload as an auxiliary power supply.
 9. A method capable of dynamicallyallocating charging current implemented by a battery management system,wherein the battery management system comprising a power supply, abattery unit, a system load, a first switch and a second switch, whereinthe second switch can turn to a forward conduction and a oppositeconduction, the method comprising: determining whether the value of thecurrent provided by the power supply is greater than a threshold value;controlling to turn on the first switch and turn the second switch tothe forward conduction when the value is greater than the thresholdvalue; and dividing the current provided by the power supply into afirst output current and a second output current according to a workingcurrent of the system load in a normal state, wherein the first outputcurrent is used to power the system load, and the second output currentis used to charge the battery unit, and the value of the second outputcurrent is changed with the variation value of the first output current.10. The method as recited in claim 9, further comprising: determiningwhether the value of the second output current is less than a cut-offcurrent value of the battery unit; determining whether the current valueis less than a maximum current value provided by the power supply whenthe second output current value is less than the cut-off current value;and determining the process of charging the battery unit to be finished,and turning off the second switch.
 11. The method as recited in claim 9,wherein when the second switch is turned to forward conduction, thesecond output current provided by the power supply is used to charge thebattery unit, and when the second switch is turned to oppositeconduction, the current provided by the battery unit is used to powerthe system load.
 12. The method as recited in claim 9, furthercomprising: determining whether the value of the second output currentdecreases to zero; and controlling the second switch to turn to oppositeconduction, and the battery unit provides current to the system loadwhen the second output current value is zero.